Why is there a sudden rush of Chinese IPOs?

We have a shot at 12 initial public offerings this week, the busiest week of the year so far. One trend stands out: The Chinese are coming. And coming.

There are three Chinese IPOs this week. Three?

"It's a case of following the money," John Fitzgibbon, founder of research firm IPO Scoop, said. "Earlier Chinese IPOs have done well and they figured there is demand here, so others keep coming."

"Investors are willing to roll the dice with China," Kathleen Smith, co-founder of Renaissance Capital, told me. "Assuming you believe China is going to have positive GDP growth, China is the biggest opportunity for new companies because China is so underpenetrated in many areas."

It's not a Chinese IPO flood yet, but it is sizeable, and it could get a lot bigger:

Chinese IPOs in the U.S.

2017 (to date): 11 2016: 7 2015: 4 2014: 16

Source: Renaissance Capital

Eleven so far this year, but nine have been since September. There have been about 44 IPOs since the beginning of September, so about 20 percent of the IPOs in that period have come from China.

That is a lot.

The good news is the average return for the nine that have gone public since November has been good: up 21.9 percent above their initial offering price.

They are not all necessarily instant gainers. Chinese education firm Four Seasons Education priced at $10 but closed Wednesday at $9.50, a five percent decline.

One key investment point: It helps to have a big company behind you when you're in a competitive space in China. Remember Secoo Holding, which sells luxury brands in China? It's down 38 percent since it went public in September. Good idea, but up against Alibaba and JD.com with no big backing? Tough sell.

Today the markets will be focused on Sogou (pronounced So-Go), the No. 2 mobile search engine in China, after Baidu. It is looking to price 45 million shares at a price of $13, the top end of its $11 to $13 a share range.

Sogou is competing with Baidu in mobile search, but Sogou has heavyweight backing: Tencent owns about 39 percent of the company, according to Renaissance Capital.

For American investors, the appeal of Chinese IPOs is understandable: access to the biggest consumer market in the world.

Smith also highlighted one big difference between the U.S. and China IPO markets: "Many U.S. companies are seeking to hide in private valuations, but not the Chinese. They are rushing to go public."